Spring assembly for aircraft components

ABSTRACT

A spring assembly elongate along a longitudinal direction includes a first spring that includes a first spring member and a first elongate member that extends from the first spring member along the longitudinal direction. The spring assembly includes a second spring including a second spring member and a second elongate member that extends from the second spring member along the longitudinal direction. The second elongate member extends through the first spring member, and the first elongate member extends through the second spring member such that the first and second spring members are spaced apart with respect to each other along the longitudinal direction.

FIELD OF THE INVENTION

The present disclosure relates to a biasing assembly for aircraftcomponents, such as landing gear for an aircraft.

BACKGROUND

Springs are used in various aircraft components. For instance, aircraftlanding gears are deployed during landing and while taxiing on therunway, and are retracted into compartments inside the aircraft during aflight. Landing gears include a main shock strut that carries a wheelassembly, side braces, locking braces, and springs connected between theside and locking braces, and various actuators that cause deployment andretraction of gears. Such springs are referred to as “downlock” springsbecause they pull the lock braces over center and into a lockedposition, locking the side braces into a down and locked positionprepared for landing in the event of hydraulic power loss. Typically, apair of downlock springs are used, each arranged to provide a biasingforce between the side and locking braces during deployment andretraction. The need for a pair of springs comes from a safetyrequirement that requires the downlocking system of springs, howevermany there are, to function and operate the locking of the side bracesin the event of hydraulic power loss or loss of one of springs. Thisparticular spring configuration takes up space, and is prone to failurewhen the springs are subject to natural frequencies. Further, suchsprings increase component cost and maintenance complexity.

SUMMARY

An implementation of the present disclosure a spring assembly configuredfor an aircraft component, such as a landing gear and the like. Thespring assembly elongates along a longitudinal direction and includes afirst spring that includes a first spring member and a first elongatemember that extends from the first spring member along the longitudinaldirection. The spring assembly includes a second spring including asecond spring member and a second elongate member that extends from thesecond spring member along the longitudinal direction. The secondelongate member extends through the first spring member, and the firstelongate member extends through the second spring member such that thefirst and second spring members are spaced apart with respect to eachother along the longitudinal direction.

The features, functions, and advantages that have been discussed can beachieved independently in various embodiments or may be combined in yetother embodiments, further details of which can be seen with referenceto the following description and drawings.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing summary, as well as the following detailed description ofan exemplary implementations of the present disclosure, will be betterunderstood when read in conjunction with the appended drawings, in whichthere is shown in the drawings example implementations for the purposesof illustration. It should be understood, however, that the presentapplication is not limited to the precise arrangements and systemsshown. In the drawings:

FIG. 1 is a perspective schematic view of a landing gear according to animplementation of the present disclosure;

FIG. 2 is a detailed view of a portion of the landing gear shown in FIG.1, illustrating the landing gear deployed and a spring assembly in afirst configuration;

FIG. 3 is a detailed view of a portion of the landing gear shown in FIG.2, illustrating the landing gear retracted into the landing gearcompartment and the spring assembly in a second extended configuration;

FIGS. 4, 5, and 6 are top, side, and end views, respectively, of one ofthe springs in the spring assembly illustrated in FIGS. 2 and 3;

FIGS. 7 and 8 are top and end views, respectively, of the other springin the spring assembly illustrated in FIGS. 2 and 3; and

FIGS. 9A and 9B are side views of the spring assembly in the firstconfiguration and the second extended configuration, respectively.

DETAILED DESCRIPTION

Referring to FIG. 1, a portion of an aircraft 10 is shown including anaircraft component, such as a landing gear 20. The landing gear 20 isconfigured to transition between a deployed configuration when theaircraft 10 is landing or taxiing about the runway, and a retracted orin-flight configuration whereby the landing gear 20 is retracted into acompartment 12 in the aircraft 10. In accordance with the exampleillustrated in FIG. 1, frames 14 a and 14 b, located in the compartment12 of the aircraft, partially support the landing gear 20. The landinggear 20 includes a shock strut 22 (sometimes referred to herein as amain support or main member) that carries a wheel assembly 24, a firstside brace 26 that is pivotably coupled to the shock strut 22 and theframe 14 a, and a locking brace 30 pivotally coupled to the shock strut22 and the first side brace 26. One or more spring assemblies 50 can becoupled between the locking brace 30 and the first side brace 26. Thelanding gear 20 also includes a second side brace 28 pivotably coupledto the shock strut 22 and the frame 14 b. The second side brace 28 isrotationally offset with respect to first side brace 26 along a forwarddirection F. The first side brace 26 can be referred to as an aft sidebrace 26, and the second side brace 28 can be referred to as a dragbrace. As is typical, the landing gear 20 includes various actuatorsconfigured to transition the landing gear 20 between the deployedconfiguration as illustrated in FIG. 1 and the retracted configuration.The landing gear 20 illustrated in FIG. 1 is a main landing gear. Itshould be appreciated that the present disclosure is applicable to anose landing gear.

FIGS. 2 and 3 illustrate the first side brace 26, locking brace 30, andthe shock strut 22 during retraction of the landing gear. The first sidebrace 26 includes a first arm 32 and a second arm 34 coupled to thefirst arm 32 at a pivot connection P1. The first arm 32 is coupled tothe shock strut 22 at the connector 33 and is further configured topivot relative to the shock strut 22. The locking brace 30 includes afirst leg 36 and a second leg 38 pivotably coupled to each other atpivot connection P2. The first leg 36 is coupled to the shock strut 22at a connector 37 and the second leg 38 is coupled to the first sidebrace 26 at the pivot connection P1. A first elongate pin 40 a disposedin the aperture or bore (not numbered) of the locking brace 30 isconnected to one end of the spring assembly 50. A second elongate pin 40b, similar to the first elongate pin 40 a, is supported by the first arm32 of the first side brace 26. The other end of the spring assembly 50is connected to the elongate pin 40 b.

In operation, as the landing gear 20 transitions from the deployedconfiguration shown in FIGS. 1 and 2 into the retracted position asshown in FIG. 3, the locking brace 30 pivots toward the shock strut 22and about the pivot connection P2 such that the first and second legs 36and 38 collapse into a folded configuration. (Portions of the lockingbrace 30 are not shown in FIG. 3.) Simultaneously, the first side brace26 also pivots toward the shock strut 22 while also pivoting about thepivot connection P1 such that the first and second arms 32 and 34collapse into a folded configuration. Because the connector 37 has beendisplaced relative to the connector 33 along a length direction (notshown) of the shock strut 22, the spring assembly 50 is extended intothe second extended configuration and biasing forces are applied to theelongate pins 40 a and 40 b. The forces applied to the elongate pins 40a and 40 b are transferred to the first leg 36 of the locking brace 30and the first arm 32 of first side brace 26, respectively. When thelanding gear is deployed, the locking brace 30 and side brace 26 pivotabout respective pivot connections P2 and P1 and the connector 37 isdisplaced back toward the connector 33. The spring assembly 50 retractsinto its initial configuration. Although not shown in FIGS. 2 and 3, thesecond side brace 28 collapses into a folding configuration as thelanding gear is retracted.

Turning now to FIGS. 9A and 9B, the spring assembly 50 is configured totransition between the initial configuration as shown in FIG. 9A and thesecond extended configuration as shown in FIG. 9B. The spring assembly50 has a first assembly end 52, a second assembly end 54 spaced apartfrom the first assembly end 52 along a longitudinal direction L, and anassembly length 55 that extends from the first assembly end 52 to thesecond assembly end 54. The assembly length 55 increases as the springassembly 50 transitions into the extended configuration. The firstassembly end 52 can be coupled to the elongate pin 40 a, which issecured to the locking brace 30 (shown in FIG. 2). The second assemblyend 54 can be coupled to the elongate pin 40 b, which is secured to thefirst side brace 26 (also shown in FIG. 2) as noted above.

Referring to FIGS. 4-6, the spring assembly 50 includes at least a firstspring 60 and a second spring 80 that are configured similarly to eachother. The first spring 60 includes a first spring member 70 and a firstelongate member 74 that extends linearly from the first spring member 70along a longitudinal direction L. The first spring 60 includes a firstend 62 and a second end 64 spaced from the first end 62 along a centralaxis 61 that is aligned with and parallel to the longitudinal directionL. The first spring 60 has a first or at-rest length 63 that extendsfrom the first end 62 to the second end 64 along the axis 61. Attachmentmembers 66 and 68, illustrated as hooks, are disposed at the opposedfirst and second ends 62 and 64, respectively, and are configured toattach directly or indirectly to the side or locking brace.

Continuing with FIGS. 4-6, the first spring member 70 as illustratedincludes a helical body 72 that includes a plurality of coils that windaround the central axis 61. In accordance with the illustrated example,the helical body 72 includes up to 7.5 right-hand wound coils. It shouldbe appreciated that more or less coils can be used. In addition, eitherright-hand wound coils or left-hand wound coils could be used. Thehelical body 72 includes an exterior side 73 e, an interior side 73 i,and an interior space 78, which may be defined at least partially by theinterior side 73 i of the helical body 72.

As shown in FIGS. 4 and 5, the first elongate member 74 is an elongaterod or wire that extends from the first spring member 70 to theattachment member 68 along the longitudinal direction L. The firstelongate member 74 includes a rod body 76 that extends along a rod axis(not shown) that is offset with respect to central axis 61 of the firstspring 60. It should be appreciated that the first spring member 70 andfirst elongate member 74 can be configured as a monolithic rod or wire.

The second spring 80 is shown in FIGS. 7 and 8. The second spring 80includes a second spring member 90 and a second elongate member 94 thatextends linearly from the second spring member 90 along the longitudinaldirection L. As illustrated, the second spring 80 includes a first end82 and a second end 84 spaced from the first end 82 along a central axis81 that is aligned with a parallel to the longitudinal direction L. Thesecond spring 80 has a first or at-rest length 83 that extends from thefirst end 82 to the second end 84 along the axis 81. Attachment members86 and 88, illustrated as hooks, are disposed at the opposed first andsecond ends 82 and 84 and are configured to attach directly orindirectly to the side or locking brace.

The second elongate member 94 may be an elongate rod or wire thatextends from the second spring member 90 to the attachment member 88along the longitudinal direction L. The second elongate member 94includes a rod body 96 that extends along a rod axis (not shown) that isoffset with respect to central axis 81 of the second spring 80. Itshould be appreciated that the second spring member 90 and secondelongate member 94 can be configured as a monolithic rod or wire.

The first and second springs 60 and 80 are arranged in the springassembly 50 so that the first elongate member 74 extends through anddoes not contact the second spring member 90 and the second elongatemember 94 extends through and does not contact the first spring member70. Further, the first and second springs 60 and 80 are not directlyattached to each other. As illustrated, the first and second springs 60and 80 are independently coupled to the elongate pins 40 a and 40 b asnoted above. The spring assembly 50 may include an optional coupler 56positioned along the elongate members of each coil so to prevent thefirst and second elongate members 74 and 94 from the contacting eachother. As illustrated, the attachment members 86 and 88, illustrated ashooks, are rotatably attached to the elongate pins 40 a and 40 b. As thefirst side brace 26 and locking brace 30 transition into theirrespective folded configurations, the attachment members 86 and 88rotate around the elongate pins 40 a and 40 b as the spring assembly 50is flexed into the extended configuration. While hooks are illustrated,the attachment members may be other devices configured to connect to theelongate pins 40 a and 40 b or first side brace 26 and locking braces30.

The second spring member 90 is similar to the first spring member 70.Specifically, the second spring member 90 includes a helical body 92defining a plurality of coils that extend around the central axis 81. Inaccordance with the illustrated example, the helical body 92 includes upto 7.5, right-hand wound coils. The windings can be right-hand orleft-hand coils as needed. The helical body 92 includes an exterior side93 e, an interior side 93 i, and interior space 98 defined at leastpartially by the interior side 93 i of the helical body 92.

Referring now to FIG. 9B, when first and second springs 60 and 80 arearranged in the spring assembly 50 the first and second elongate members74 and 94 extend through interior spaces 78 and 98 of the first andsecond springs 60 and 80, respectively. Further, each elongate member 74and 94 is offset from the central axes 61 and 81 of the other elongatemember. Because each spring 60 and 80 is similar, for example each hassimilar helical bodies and the elongate members 74 and 94 extend throughrespective spring members 70 and 90, space utilization is improvedwithout compromising landing gear integrity. Such similarities alsomaximize part utilization in the landing gear assembly, which can resultin cost savings.

Continuing with FIGS. 9A and 9B, the first and second spring members 70and 90 elongate when one or both of the first and second assembly ends52 and 54 are subjected to a pulling force. As illustrated, the firstspring member 70 defines a spring length 75 that extends from its firstouter segment 77 to its second outer segment 79 along the longitudinaldirection L. In addition, the second spring member 90 defines a springlength 95 that extends from its first outer coil segment 97 to itssecond outer segments 99 along the longitudinal direction L. Eachrespective spring member length 75 and 95 can be no greater than half ofthe assembly length 55 when in the extended configuration. In certainexamples, the individual spring lengths 75 and 95 are no greater thanabout 25% of the assembly length 55. In embodiments where the coupler 56is used, the spring lengths 70 and 90 should be selected so as to definea gap (not numbered) between each respective helical body in theextended configurations. The gap defines a space for the placement ofthe coupler 56. In other words, the gap should be configures so that thehelical bodies 72 and 92 do not contact the coupler 56 during extension.

Another implementation of the present disclosure is a method forassembling a landing gear. The method includes first constructing thefirst and second springs 60 and 80 from a metallic wire or rod. Therequired number of coils is formed into the wire or rod to define thespring member. The first and second ends 52 and 54 of the wire or rodextend outward from the first and second spring member 70 and 90 and canbe formed into attachments members, such as hooks, that are sized toreceive the elongate pins 40 a and 40 b. As needed the optional coupler56 can be secured to the elongate members of each spring so as toprevent the elongate members from contacting each other during use asnoted above. Then, the formed first and second springs 60 and 80 can beinstalled on the landing gear assembly as the spring assembly 50.Alternatively, the first and second springs 60 and 80 can be attached tothe elongate pins 40 a and 40 b, then the first and second springs 60and 80 and the elongate pins 40 a and 40 b can be installed in thelanding gear assembly. Other components of the landing gear, such as thelocking brace and drag brace are assembled.

The method for assembling the landing gear includes other steps as well.For instance, in one example, the method includes coupling the firstside brace 26 to the shock strut 22, and coupling the locking brace 30to the shock strut 22 and the first side brace 26. The spring assembly50 can be attached to the locking brace 30 and the first side brace 26as illustrated in FIG. 2. The pins 40 a and 40 b are located in therespective braces 26 and 30 at this point. A spring stretching tool (notshown) is used to extend the spring assemblies from a free length toinstalled or pin-pin length for installation on the braces 26 and 30.Prior to attaching the spring assemblies to the stretching tool, bothhelical bodies and elongate members are mounted to the spring ends alongwith the optional coupler. Then, the stretching tool is located betweenthe ends (of each spring assembly) so as to stretch both the springassembles to the desired “pin to pin” length. Next, the tool andstretched springs are offered up to both the pins installed in thebraces 26 and 30 at the same time and the spring ends are slid onto thepins. Thus, it can be said that during the first end 52 of the springassembly 50 is attached to the locking brace 30, and the second end 54of the spring assembly 50 to the first side brace 26, which can occursimultaneously. The second spring assembly would be attached similarlyas well. In alternative methods, the spring assemblies can be attachedto the pins sequentially. In accordance with the alternative embodiment,it can be said that during the ends of the spring assembly 50 areattached to the locking brace 30 and the first side brace 26. Then, theends of the spring assembly 70, are attached to the locking brace 30 andthe first side brace 26. In still alternative methods, each respectiveend can be attached to the respectively brace 26 and 30 sequentially. Itshould be appreciated that the methods described herein encompassinitial manufacturing of the landing gear 20 as well as maintenanceand/or repair of the landing gear 20, such as when the spring assembly50 is being replaced on an in-service aircraft.

The spring assembly 50 as described herein has several advantageousfeatures when installed in the landing gear. As assembled and placed inthe land gearing, the spring assembly 50 can reduce working stress onthe springs and improve fatigue life. For instance, when using singlesprings independently attached to the side brace of the landing gear,common resonant frequencies between adjacent springs create possiblecontact events, thereby increasing working stress on the springs.Because resonant frequency issues are minimized when utilizing thespring assembly as described herein, working stresses on the individualsprings are reduced and fatigue life of the spring assembly 50 asinstalled is improved. Further, as the number of spring assemblies canbe increased using this design negating the need for a highly loadedspring that reduces working stresses of each individual spring.

A landing gear is described as one implementation for using the springassemblies as described herein. It should be appreciated that the springassemblies can be used with other aircraft components where springs areused to control deployment of components and the like. For instance, thespring assembly can be used in systems that control deployment ofcompartments and hatch covers and the like.

What is claimed:
 1. A landing gear configured to transition between adeployed configuration and a retracted configuration in a compartment ofan aircraft, the landing gear comprising: a main member; a side bracecoupled to the main member; a locking brace coupled to the main member;and a spring assembly coupled to the side brace and the locking brace,the spring assembly elongate along a longitudinal direction and furtherincluding: a first spring that includes a first spring member and afirst elongate member that extends from the first spring member alongthe longitudinal direction; and a second spring that includes a secondspring member and a second elongate member that extends from the secondspring member along the longitudinal direction, wherein the firstelongate member extends through the second spring member and the secondelongate member extends through the first spring member such that thefirst and second spring members are spaced apart with respect to eachother along the longitudinal direction.
 2. The landing gear of claim 1,wherein each spring includes a first end and a second end spaced opposedto the first end, the first and second ends of each spring include anattachment member configured to be moveably coupled to side brace. 3.The landing gear of claim 2, wherein each attachment member is a hook.4. The landing gear of claim 3, wherein the respective hooks of thefirst ends of the springs are attached to a first pin positioned on theside brace and the respective hooks of the second ends of the springsare attached to a second pin positioned on the locking brace.
 5. Thelanding gear of claim 1, wherein the first and second spring members donot contact the first and second elongate members.
 6. The landing gearof claim 1, wherein the first spring will perform the desired functionin the event the second spring fails.
 7. The landing gear of claim 1,wherein the spring assembly includes a first end, a second end spacedfrom the first end in a longitudinal direction, and a length thatextends from the first end to the second end, wherein the length of thespring assembly increases as the spring assembly transitions from afirst configuration into a second extended configuration.
 8. The landinggear of claim 1, further comprising a landing wheel assembly supportedby the main member.
 9. A method of transitioning a landing gear betweena deployed configuration and a retracted configuration in a compartmentof an aircraft, the method comprising: coupling a side brace to a mainmember; coupling a locking brace to the main member; and coupling aspring assembly to the side brace and the locking brace, the springassembly elongate along a longitudinal direction and further including:a first spring that includes a first spring member and a first elongatemember that extends from the first spring member along the longitudinaldirection; and a second spring that includes a second spring member anda second elongate member that extends from the second spring memberalong the longitudinal direction, wherein the first elongate memberextends through the second spring member and the second elongate memberextends through the first spring member such that the first and secondspring members are spaced apart with respect to each other along thelongitudinal direction.
 10. The method of claim 9, wherein the first andsecond spring members do not contact the first and second elongatemembers.
 11. The method of claim 9, wherein each spring includes a firstend and a second end spaced opposed to the first end, the first andsecond ends of each spring include an attachment member configured to bemoveably coupled to respective structures.
 12. The method of claim 11,wherein each attachment member is a hook configured to attach to anelongate pin.
 13. The method of claim 9, wherein the spring assemblyincludes a first end, a second end spaced from the first end in alongitudinal direction, and a length that extends from the first end tothe second, wherein the length of the spring assembly increases as thespring assembly transitions from a first configuration into a secondextended configuration.
 14. The method of claim 13, wherein each springmember is a coil and each elongate member is a linear rod.
 15. Themethod of claim 14, wherein each coil elongates when the spring assemblyis in the second extended configuration.
 16. The method of claim 9,wherein the first spring and the second spring are duplicate parts. 17.The method of claim 9, wherein the first spring and second spring eachhave approximately the same diameter and spring rate.
 18. The method ofclaim 9, wherein the first and second spring assemblies attach to astructure at the same points and are centered about common central axis.19. The method of claim 9, wherein the coupling the spring assembly tothe side brace and the locking brace includes: attaching a first end ofthe spring assembly to the side brace; and attaching a second end of thespring assembly to the locking brace.
 20. The method of claim 19,wherein each spring includes first and second opposed ends, and thefirst attaching step includes: attaching respective first ends of thefirst and second springs to a first pin; and attaching the first pin tothe side brace.
 21. The method of claim 19, wherein the second attachingstep includes: attaching respective second ends of the first and secondsprings to a second pin; and attaching the second pin to the lockingbrace.
 22. The method of claim 9, further comprising extending, via atool, each spring from a first length to an extended length.
 23. Themethod of claim 9, further comprising placing a coupler between theelongate members of each spring so as to prevent the elongate memberfrom contacting each other.